BGE: How to apply colour to a certain face with python?
If you don't need to apply coloir to that face in-game you can add different material to it without python- in materials tabe add ne material to mesh on the left of the list of materials. Than set that material to the color you want and go in edit mode. Than select the face you want to be colored in that color and select it(only). After that stay in edit mode and go to materials tab. Selec the material you want to apply on your face and than press assign under list of materials in materials tab!